Switches for activating and deactivating circuits to perform various functions are commonly employed, especially in vehicles. One such switch which is frequently encountered is a so-called courtesy switch which derives its name from its usual function of turning on a light as an aid to the operator of the vehicle as he enters or exits the vehicle. Similar switches are often used to turn on a light when, for example, a trunk lid is lifted, an engine hood is lifted, or a glove compartment door is opened. Practically all such switches include an actuating plunger or lever which moves generally under spring pressure when the spacing is increased between fixed and movable members. Whether the movable member is a passenger door, a trunk lid, a hood, a tailgate, or a glove compartment door, the switches have one common problem. Mass-produced vehicles necessarily have some manufacturing tolerances in the dimensions of elements designed to fit relative to each other. As a result, a switch designed for such use as in the door post of a vehicle must be capable of operation in response to the opening and closing of doors which may be closely or loosely fitted relative to that door post.
Efforts have been made to accommodate the varying gaps which are encountered in a run of mass-produced vehicles. One expedient has been to permit overtravel as needed in the actuating member of the switch, but the excessive length of such switches leads to early failure. Other efforts have been made to give the switch a degree of self-adjustment using, for example, such items as telescoping sleeves in the switch body, but too often these have been ineffective or unduly expensive.
Another persistent problem relates to the environment in which the switches are used. Most of the switches with which the present invention is concerned are so positioned relative to the exterior of the vehicle that they are exposed to weather and environmental conditions which may reach extremes, depending upon the geographical area where the vehicle is used. Clearly, a door switch may be thoroughly soaked in a rain storm; ice or snow may enter and melting or freezing in the switch area interferes with the operation of the switch. Even dust or dirt may interfere with switch operation if it accumulates in critical areas.